RFR: JDK-8344057 : Remove doPrivileged calls from unix platform sources in the java.desktop module [v3]

[Harshitha Onkar]

> Post JEP-486 (Permanently Disable the Security Manager) cleanup.
> Calls to java.security.AccessController.doPrivileged are obsolete thus removed in this PR.
> 
> This PR addresses removal of AccessController.doPrivileged() calls from unix-platform files in the java.desktop module. Any SM related imports that are no longer needed are removed.
> 
> This PR is limited to removing doPrivileged() calls and excludes any refactoring, reformatting, or other clean up that is out-of-scope for this fix.
> 
> PS: I have explicitly add comments to the changes where a more watchful review is required.

Harshitha Onkar has updated the pull request incrementally with one additional commit since the last revision:

  spacing

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Changes:
  - all: https://git.openjdk.org/jdk/pull/22218/files
  - new: https://git.openjdk.org/jdk/pull/22218/files/26112aa7..ef2603ad

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22218&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22218&range=01-02

  Stats: 3 lines in 3 files changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/22218.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22218/head:pull/22218

PR: https://git.openjdk.org/jdk/pull/22218